Anticoagulation in Older Adults

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Anticoagulation in Older Adults

• Seki Balogun MD

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Introduction

• In older adults
• Many common cardiovascular disorders are
  associated with risk of thrombosis
• Higher disease burden and polypharmacy leading to
  increased risk of drug drug or drug-disease
  interaction
• Often, an overall assessment of risks vs.
  benefits is required

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Practical issues

• Age often a deterrent to the use of
  anticoagulants (warfarin or heparin)
• Age is an independent risk factor for
  anticoagulant-induced bleeding
• Rate of major hemorrhage in age gt80 years is
  almost 3 times that in a person who is lt60 years

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Factors that increase the risk of bleeding in
older adults

• Increased sensitivity to the effect of
  anticoagulation
• increased receptor affinity
• lower vitamin K intake
• Concurrent use of many drugs that increase
  bleeding risk or affect warfarin metabolism
• Other co-morbidities that increase risk of
  bleeding
• Diverticulosis
• Uncontrolled HTN
• Malignancy
• Thrombocytopenia

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Factors that increase the risk of bleeding in
older adults

• Poor compliance
• Cognitive impairment
• Functional Impairment
• Personal beliefs
• Trauma risks (falls gait instability, peripheral
  neuropathy)
• Issues with monitoring patients (i.e. remote
  areas, difficult transportation)
• History of GI bleeding
• History of ICH (amyloid angiopathy, elevated BP)
• Excessive anticoagulation (INR gt4)

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Anticoagulation Agents

• Warfarin
• Heparin
• Unfractionated heparin
• Low molecular weight heparin

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Warfarin

• Inhibits gamma carboxylation of vitamin K-
  dependent factors (II, VII, IX, X)
• Thrombogenic effect (initially)
• Inhibit vitamin K dependent gamma carboxylation
  of Protein C and S (inhibitors of coagulation)
• Peak effect 36 72 hours
• Full anticoagulation 5- 7days
• Monitoring PT/INR

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Warfarin

• Initial dose 5 mg daily or less in the elderly
• Dose adjusted based on INR
• Drug interactions
• Antibiotics
• Gingko biloba
• NSAID and Aspirin
• May increase risk of bleeding

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Warfarin Complications

• Bleeding
• Increased when INR gt3
• Treatment Vit K, FFP (if bleeding profuse or
  unresponsive to Vit K)
• Skin necrosis (large doses, Protein C deficiency)
• Due to rapid reduction in protein C

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Heparin

• Indirect thrombin inhibitor which complexes with
  antithrombin and converts this to an inactivator
  of thrombin and several clotting factors (X, XII,
  XI, IX)
• Complications
• Bleeding
• Reversed with protamine sulfate
• Heparin-induced thrombocytopenia
• usually occurs within 5 to 10 days
• Osteoporosis

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Common indications encountered during geriatric
rehabilitation

• A. Prevention of venous thromboembolic disease
• Post- Surgery
• Conditions leading to immobility
• Acute spinal cord injury
• Hospitalization and deconditioning
• Stroke (useful in secondary prevention in pts
  with atrial fibrillation)
• Multiple trauma

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Common indications

• B. Atrial Fibrillation
• C. Anticoagulation in heart failure
• D. Prosthetic heart valves
• E. Treatment of transient ischemic attack and
  minor stroke

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Prevention of venous thromboembolic disease

• Surgery
• Low risk
• lt 40 yrs, no risk factors
• GA lt30mins
• Minor elective, abdominal or thoracic sx
• Risk of prox. DVT 1, PE lt0.01
• Risk factors Advanced age, prior DVT/PE.,
  Obesity, heart failure, paralysis,
  hypercoagulable state (protein C deficiency,
  factor V Leiden)

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Surgery

• Moderate risk
• gt40 yrs, one or more risk factor
• GA gt30mins
• Risk prox. DVT 2-10, PE0.1 0.7
• High risk
• gt40 yrs, one or more risk factors
• Orthopedic or surgery for malignancy
• Spinal cord injury
• Risk prox. DVT10-20, PE 1-5

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DVT prophylaxis in low risk surgical patients

• Early ambulation
• Graduated compression stockings
• Reduce post-op venous thrombosis

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DVT prophylaxis in moderate risksurgical patients

• Low dose unfractionated heparin or LMWH
• Both equally effective
• Less bleeding and thrombocytopenia seen with LMWH
• LMWH once daily dosing but more expensive
• Intermittent Pneumatic compression
• Alternative for pts at high risk of bleeding
• May be uncomfortable
• Not used in severe PVD with ischemia
• May cause new clot to dislodge

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DVT prophylaxis in high risksurgical patients

• Elective knee replacement
• LMWH 30mg every 12hrs SC
• Usually started 12-24hrs post op
• Oral anticoagulation (warfarin)
• Target INR 2.5 (range 2 -3 )
• Prophylaxis duration 7 -10 days
• Prolonged prophylaxis does not appear to provide
  further benefit
• Less total DVT with LMWH
• Incidence of proximal DVT about the same

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DVT prophylaxis in high risksurgical patients

• Hip Replacement
• LMWH 30 mg every 12hrs or 40 mg daily SC
• Warfarin Target INR 2.5 (range 2 3)
• Started 12- 24hrs post op
• Duration at least 10 days
• Extended prophylaxis 27 35 days (4 -5 weeks)
  significantly reduces the incidence of total DVT
  and PE, without an increase in major bleeding

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High risk surgical patients

• Hip Fracture
• LMWH or low-dose unfractionated heparin
• Reduces the risk of deep venous thrombosis by 64
  percent
• Warfarin INR range 2 -3
• Start preoperatively 12 hrs
• No data on duration of anticoagulant therapy.

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Hip Fracture

• Reasonable to continue prophylaxis until the
  patient is fully ambulatory
• Extended prophylaxis in those with high risk of
  deep venous thrombosis  
• Aspirin (325 mg to 650 mg per day)
• If unable to take heparin or warfarin
• Less effective

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Newer agents

• Fondaparinux (Arixtra)
• Synthetic heparin
• Approved by FDA in 2001
• Used in DVT prophylaxis in major orthopedic
  surgery (THA, TKR, hip fracture)
• More effective than LMWH
• More expensive

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Acute spinal cord injury

• Greatest risk for DVT 72 hrs - 2 weeks
• venous stasis from lower extremity paralysis and
  immobility
• platelet and coagulation abnormalities
• vascular intimal injury
• DVT prevention
• LMWH
• Most effective and preferred

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Acute spinal cord injury

• Adjusted dose unfractionated heparin (APTT of
  1.5)
• As effective as LMWH
• Low dose unfractionated heparin
• Inadequate as monotherapy 
• Effective when combined with Intermittent
  pneumatic compression
• Warfarin
• Appears to be effective but based on anecdotal
  evidence
• Duration of therapy about 3months (decline in
  risk of DVT )
• Maybe extended in patients who are bed-ridden or
  have other significant risk factors for venous
  thromboembolism

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Hospitalization and deconditioning

• Common complication
• Increases with advancing age
• Only about 43 of medical patients receive DVT
  prophylaxis
• Prophylaxis reduces DVT and PE
• No decrease in mortality
• Prophylaxis
• Low dose heparin or LMWH
• IPC if at high risk for bleeding

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Multiple trauma

• LMWH
• Most effective and better than low dose heparin
• Start as soon as considered safe
• IPC
• In those with high risk of bleeding

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Atrial Fibrillation

• Warfarin
• Used in AF with moderate or high risk of stroke
• Age gt65
• Previous TIA or Stroke
• HTN
• CHF
• Valvular heart disease
• Secondary prevention of ischemic stroke in pts
  with Afib
• Anticoagulation started at least 2 weeks after
  stroke
• Hemorrhagic conversion

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Atrial Fibrillation

• More effective in women than in men (84 and 60
  risk reduction)
• Benefit even in AF patients who developed a
  stroke while taking warfarin
• Reduced mortality by 33

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Anticoagulation in heart failure

• High risks for thromboembolism in CHF
• Presence of Atrial fibrillation
• Previous thromboembolic event
• Presence of left ventricular thrombus
• Symptomatic heart failure with markedly reduced
  LVEF (lt30), regardless of etiology
• Presence of a large akinetic region of the left
  ventricle or mural thrombus following myocardial
  infarction
• Less established evidence class IIb

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Patients with prosthetic heart valves

• Mechanical Prosthetic valves
• Anticoagulation depends upon the location, type
  or number of valves
• Warfarin INR 2.5 3.5
• LMWH or Unfractionated heparin until INR is
  therapeutic
• Combination with low dose aspirin 80 100mg/day
  recommended in certain cases
• Life- long

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Bioprosthetic valves

• Anticoagulation
• Warfarin INR 2-3
• Duration 3months
• LMWH or Unfractionated heparin until INR is
  therapeutic